The present invention relates to a self-contained vehicle refrigeration unit, and more particularly, to a self-contained vehicle refrigeration unit having a relatively compact construction and an evaporator section located in the same housing as a vehicle refrigeration unit drive system so that the evaporator section does not protrude into a payload space or cargo space of a vehicle body.
Conventional vehicle refrigeration units typically include a refrigeration unit drive system mounted within a unit housing attached to a vehicle body above a vehicle cab. The conventional refrigeration unit drive systems have a driving motor connected to at least one driven component via several belts and a plurality of pulleys mounted on the driven component and the driving motor. Because a plurality of pulleys and belts are used, the refrigeration unit drive system occupies a relatively large amount of space in the refrigeration unit housing. This relatively large space requirement prevents all of the components of the vehicle refrigeration unit from being mounted on the outside of the vehicle body and within the unit housing.
As a result, the evaporator section of conventional vehicle refrigeration units must be mounted within a vehicle body thereby reducing the amount of payload or cargo space of the vehicle body. This is disadvantageous because of the wasted payload space and because the components of the evaporator section increase the difficulty of loading of the vehicle body because the evaporator section inside of the vehicle body must be avoided. In fact, people loading objects in the vehicle body often strike their heads and/or shoulder on the components of the evaporator section.
Furthermore, the conventional vehicle refrigeration units are not easily accessible for maintenance and repair. Because the evaporator section is located within the vehicle body and the remaining elements of the refrigeration unit are located in the unit housing, a repair person may have to gain access to both the vehicle body and the refrigeration unit housing to complete a maintenance or repair operation. In some cases, a repair may require that one repair person work in the unit housing while another person works in the vehicle body, thereby increasing the amount of time and expense of repairing or maintaining the refrigeration unit.
One conventional refrigeration unit has overcome the problem with the evaporator section protruding into the payload space of the vehicle body. Welch, U.S. Pat. No. 4,811,569, teaches a transport refrigeration unit in which an evaporator 150 is located in the same housing as the other refrigeration unit components so that an evaporator blower does not protrude into the payload space of the vehicle body.
However, the drive system of this refrigeration unit is complicated and requires a plurality of pulleys and drive belts. This increases the time and difficulty involved in assembling the refrigeration unit, as well as, making it more difficult to service the unit. Also, both the evaporator blower 122 and the condenser fan 120 are driven by a main drive shaft 116 which extends along the length of the refrigeration unit housing thereby increasing the space requirements of the drive system. Also, if one of the driven components driven by the main drive shaft 116 seizes suddenly, the drive shaft 116 may be damaged by the extreme torque created by the stoppage of the seized drive component. Then, the drive shaft 116 would have to be replaced which is difficult and expensive. Also, because of the nature of the drive system, air from the condenser 170 must be directed from one side of the unit, along the entire length of the drive system and out an opposite side of the unit as seen in FIG. 5.